Pedicle screw constructs for spine fixation systems

ABSTRACT

A pedicle screw coupling construct for a pedicle screw construct provides fixation of angular orientation thereof relative to a pedicle screw independent of fixation of a received spinal rod to the coupling construct. The pedicle screw construct forms one component or element in a spinal fixation system. The independent fixation coupling construct also provides for fixation of the angular orientation of the coupling construct while the coupling construct has received the spinal rod. In another form, a coupling head or construct is configured to allow a pedicle screw shaft to pass therethrough but retain the pedicle screw head for rotation of the coupling head about the pedicle screw head. The coupling head or construct is also configured to allow at least a 45° arc of pivot or articulation about a pedicle screw shaft relative to a longitudinal axis of a spinal rod received in the body. This allows the head with a received spinal rod to fold, bend or pivot relative to the pedicle screw shaft, particularly to a greater degree than the prior art.

This U.S. non-provisional patent application is a continuation of U.S.patent application Ser. No. 11/034,300 titled “PEDICLE SCREW CONSTRUCTSFOR SPINE FIXATION SYSTEMS” filed Jan. 12, 2005, the full disclosure ofwhich is hereby incorporated herein by reference; which claims thebenefit of and/or priority to U.S. provisional patent application Ser.No. 60/536,319 filed Jan. 13, 2004 entitled “Pedicle Screw Construct fora Spine Fixation System”, the entire contents of which is specificallyincorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to spinal fixation devices forthe internal fixation of the spine particularly within the fields oforthopedics and/or neurosurgery such as spinal implants and rods forholding vertebral bones fixed relative to one another and, moreparticularly, to a polyaxial pedicle screw and/or coupling apparatus foruse in spinal surgical procedures for receiving a rod for stabilizingthe relative motion of vertebrae.

The spinal column of bones is a highly complex structure that not onlyallows a high degree of flexible movement in various directions, butalso envelopes and protects numerous veins, arteries and nerves of thebody. The adult human spine consists of over twenty discrete bones thatare coupled sequentially to one another through posterior facet jointsand discs of cartilage (known as intervertebral discs or simply, discs)positioned between adjacent vertebrae. The facet joints and discs allowthe spine to bend and twist. Different muscles coordinate movement inmany directions.

Areas of the spine have been anatomically categorized. Thus, bones ofthe spine are anatomically classified as being from one of four areas orclassifications, namely, the cervical, thoracic, lumbar, or sacralareas. The various areas of the spine also have a natural orcharacteristic curvature or curve. The four curves of the spine areknown as the cervical lordosis, the thoracic kyphosis, the lumberlordosis and the sacral kyphosis.

Genetic or irregularities such as developmental irregularities, trauma,tumors, disease and the like, however, can result in spinal pathologiesthat either limit the range of normal spinal motion or that threatensthe integrity of elements of the nervous, circulatory and/or othersystems of the spine. In these cases and others such as spinal curvatureproblems, a spinal fixation system may be used in order to immobilizevarious vertebrae. Various systems have been devised to provide thenecessary vertebrae immobilization. These spinal fixation systems areimplanted on or in the spine (spinal column). Such spinal fixationsystems or assemblies may be classified as anterior, posterior orlateral implants. Lateral and anterior fixation assemblies are attachedto the lateral and anterior portions of the spine. Posterior implantsgenerally include a pair of rods that are along the axis to which thevertebrae are to be disposed and then attached to the vertebrae byeither hooks that couple to the lamina or transverse process of thevertebrae, or by screws that are inserted into the pedicles thereof.

Rod assemblies as spinal fixation systems generally comprise a pluralityof bone or pedicle screws that are implanted into the posterior lateralsurfaces of the laminae, through the pedicles and into their respectivevertebral bodies. Each screw includes a coupling device for receivingand retaining a section of a spinal rod. The rod extends along the axisof the spine being attached to the plurality of pedicle screws throughtheir respective coupling device. The rigidity of the spinal rod may beutilized to align the spine in conformance with a desired shape.

Considerable difficulty, however, was encountered with inserting fixedscrews along a misaligned curvature and then simultaneously exactlypositioning the coupling devices such that the spinal rod receivingportions of the coupling devices were aligned such that the spinal rodcould be passed therethrough without distorting the screws. Because ofsuch difficulty, polyaxial screw and coupling devices have beendeveloped that allow limited movement of the coupling device relative tothe implanted screw. Once a desired position is achieved, the couplingdevice is fixed relative to the screw.

However, while the prior art is replete with polyaxial screw andcoupling devices for spine fixation systems, they only permit a limitedfreedom of movement with respect to angulation of the screw and thecoupling device. Moreover, these prior art polyaxial screw and couplingdevices are generally complex, inadequately reliable, and lack long-termdurability. Furthermore, these prior art polyaxial screw and couplingdevices do not allow the independent fixation of screw to couplingdevice angulation and rod fixation. These considerable drawbacksassociated with prior art systems also include difficulty properlypositioning the rod and coupling devices, and the tedious manipulationof the many small parts in the operation environment.

In view of the above, it is therefore an object of the present inventionto provide a pedicle screw and rod coupling device assembly thatprovides polyaxial freedom of screw implantation angulation with respectto rod reception.

It is also an object of the present invention to provide a pedicle screwconstruct that provides independent fixation of angulation of the rodcoupling device relative to the pedicle screw and of the spinal rod tothe rod coupling device.

It is further an object of the present invention to provide a pediclescrew construct that provides angular reception of the spinal rod by therod coupling device.

Accordingly, it is also an object of the present invention to provide apedicle screw construct and/or spinal rod fixation assembly that isreliable, durable and which gives long term spinal fixation support.

These needs and/or objects, and others are accomplished throughapplication of the principles of the subject invention and/or asembodied in one or more various forms and/or structures such as areshown and/or described herein.

SUMMARY OF THE INVENTION

The present invention provides various embodiments of a pedicle screwconstruct and/or a coupling construct for a pedicle screw for coupling aspinal rod relative to the pedicle screw. The pedicle screw constructmay be part of a spine fixation system consisting of one or moreconnecting rods and one or more pedicle screw constructs. Adjunctivecomponents, not forming a part of the subject invention, may be addedsuch as cross members (that link parallel systems together), hooksand/or the like.

In one form, a coupling construct provides fixation of angularorientation of the coupling construct relative to the pedicle screwindependent of the fixation of a spinal rod to the coupling construct. Apedicle screw construct including the present coupling construct formsone component or element in a spinal fixation system. The independentfixation coupling construct also provides for fixation of the angularorientation of the coupling construct while the coupling construct hasreceived the spinal rod.

In one form, a coupling construct allows a pedicle screw shaft to passtherethrough but retain the pedicle screw head for rotation of thecoupling head about the pedicle screw head and allow at least a 45° arcof pedicle screw shaft articulation relative thereto, such as to andabout a longitudinal axis of a spinal rod received in the body.

The coupling construct is utilized on a pedicles screw to form a pediclescrew construct along with other components that allows articulation ina superior/inferior (head/toe) direction and a medial/lateral(side/side) direction.

In one particular form, there is provided a pedicle screw couplingdevice for holding a spinal rod relative to a pedicle screw. The pediclescrew coupling device includes a coupling head, a tubular sleeve, acollar and a spinal rod retention element. The head has a bore defininga first end sized to receive a pedicle screw shaft and a pedicle screwhead of a pedicle screw, and a second end sized to allow the pediclescrew shaft to pass through but rotatably retain the pedicle screw head.The coupling head further includes a channel configured for reception ofa spinal rod. The tubular sleeve is configured for reception in thecoupling head bore and has a first and second end, the first endconfigured to abut the pedicle screw head. The collar is configured forreleasable fixation onto the coupling head and to abut the second end ofthe tubular sleeve to apply pressure onto the pedicle screw head throughthe first end of the tubular sleeve to fix an orientation of thecoupling head relative to the pedicle screw head. The spinal rodretention element is configured to be received through the collar and tofix a spinal rod received in the spinal rod channel of the coupling headrelative to the coupling head, the fixation of the spinal rod relativeto the coupling head independent of the fixation of the coupling headrelative to the pedicle screw head.

In another particular form, there is provided a pedicle screw couplinghead for holding a spinal rod relative to a pedicle screw having pediclescrew head and a pedicle screw shaft. The pedicle screw coupling headincludes a body, a channel formed in the body and configured to receivea spinal rod, and a pedicle screw bore formed in the body and having afirst end sized to receive a pedicle screw shaft and a pedicle screwhead of a pedicle screw and a second end sized to allow the pediclescrew shaft to pass through but retain the pedicle screw head, thesecond end configured to allow rotation of the coupling head about thepedicle screw head and to allow the body to pivot relative to thepedicle screw shaft in an arc perpendicular to a longitudinal axis of aspinal rod received in the channel, the arc defining a length of travelof substantially −5° to substantially +45° relative to an axis definedby the pedicle screw shaft.

In another particular form, there is provided a method of fixing aspinal rod relative to a pedicle screw in a spine fixation system. Themethod includes the steps of: (a) providing a pedicle screw couplingdevice having a body, a channel formed in the body and configured toreceive a spinal rod, a pedicle screw bore formed in the body and havinga first end sized to receive a pedicle screw shaft and a pedicle screwhead of a pedicle screw and a second end sized to allow the pediclescrew shaft to pass through but retain the pedicle screw head, thesecond end configured to allow rotation of the coupling head about thepedicle screw head and to allow the body to pivot relative to thepedicle screw shaft in an arc perpendicular to a longitudinal axis of aspinal rod received in the channel, the arc defining a length of travelof substantially −5° to substantially +45° relative to an axis definedby the pedicle screw shaft; (b) attaching the pedicle screw couplingdevice to a pedicle screw; (c) inserting a spinal rod into the spinalrod channel; and (d) fixing an arcuate orientation of the couplingdevice relative to the pedicle screw.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other features and objects of this invention,and the manner of attaining them, will become more apparent and theinventions will be better understood by reference to the followingdescription of embodiments of the invention taken in conjunction withthe accompanying drawings, wherein:

FIG. 1 is an exploded perspective view of a pedicle screw construct inaccordance with the present principles for holding a spinal rod relativeto a pedicle screw in a spine fixation system;

FIG. 2 is a sectional view of the locking sleeve of the pedicle screwconstruct of FIG. 1;

FIG. 3 is a bottom view of the retaining collar of the pedicle screwconstruct of FIG. 1;

FIG. 4 is a sectional view of the pedicle screw construct of FIG. 1assembled onto the pedicle screw, taken along line 4-4 thereof;

FIG. 5 is another sectional view of the pedicle screw construct of FIG.1 assembled onto the pedicle screw, taken along line 3-3 thereof;

FIG. 6 is a perspective view of the pedicle screw construct of FIG. 1assembled onto a pedicle screw and holding a spinal rod relativethereto, the pedicle screw illustrated in two positions relative to thehead of the pedicle screw construct illustrating the limits of the rangeof angular orientations of the pedicle screw relative to the head of thepedicle screw construct;

FIG. 7 is a perspective view of another embodiment of a head for apedicle screw construct in accordance with the principles of the subjectinvention;

FIG. 8 is a perspective view of the pedicle screw construct head of FIG.5 relative to a pedicle screw illustrating the limits of the range ofangular orientations of the pedicle screw relative to the pedicle screwconstruct head;

FIG. 9 is a top perspective view of another embodiment of a head for apedicle screw construct in accordance with the principles of the subjectinvention;

FIG. 10 is a bottom perspective view of the pedicle screw construct headof FIG. 9;

FIG. 11 is a perspective view of a holding collar for a pedicle screwconstruct utilizing the pedicle screw construct head of FIGS. 9 and 10;

FIG. 12 is a perspective view of a pedicle screw construct utilizing thehead of FIGS. 9 and 10 along with the collar of FIG. 11 assembled onto apedicle screw and holding a spinal rod;

FIG. 13 is an enlarged portion of the pedicle screw assembly of FIG. 12in sectional view;

FIG. 14 is an exploded perspective view of another embodiment of apedicle screw construct in accordance with the present principles forholding a spinal rod relative to a pedicle screw in a spine fixationsystem;

FIG. 15 is a side view of the pedicle screw construct of FIG. 14assembled onto the pedicle screw;

FIG. 16 is an end view of the pedicle screw construct of FIG. 14assembled onto the pedicle screw;

FIG. 17 is a sectional view of the assembled pedicle screw construct ofFIG. 16 taken along line 17-17 thereof;

FIG. 18 is a top view of the assembled pedicle screw construct of FIG.16;

FIG. 19 is a perspective view of the pedicle screw construct of FIGS.14-18 shown receiving a spinal rod;

FIG. 20 is the perspective view of FIG. 19 illustrating the manner ofloading the spinal rod;

FIG. 21 is a perspective view of another embodiment of a pedicle screwconstruct head in accordance with the present principles;

FIG. 22 is a front view of an assembled pedicle screw constructutilizing the head of FIG. 21 shown in receipt of a spinal rod beforeloading thereof; and

FIG. 23 is a sectional view of FIG. 22 taken along line 23-23 thereof,the pedicle screw of which is shown in various angular orientationsrelative to the head illustrating the range of angular orientations ofthe pedicle screw relative to the head in accordance with the principlesof the present invention.

Corresponding reference characters indicate corresponding partsthroughout the several views. Although the drawings represent variousembodiments of the invention, the drawings are not necessarily to scaleand certain features may be exaggerated in order to better illustrateand explain the invention. Also, the exemplifications set out hereinillustrate various embodiments of the invention, but suchexemplifications are not to be construed as limiting the scope of theinvention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, there is depicted an exploded view of an embodimentof a spinal rod fixation device, construct or assembly, generallydesignated 30. The spinal rod fixation device 30 is used as a componentin a spinal rod type spine fixation system or assembly. Particularly,the spinal rod fixation device 30, consisting of a coupling device,construct or assembly 31 and a pedicle screw 32, is used to attach orfix a section of a spinal rod (not shown) of the spine fixation assemblyrelative to a vertebrae of the spine. More particularly, the pediclescrew 32 is configured, adapted and/or operable to be attached to avertebra in a known manner, while the coupling construct 31 receives andfixes, retains or holds the section of the spinal rod (the spinal rod isfixed to the coupling construct). The coupling construct 31 is movablypositionable relative to the pedicle screw 32 as further describedherein. The coupling construct 31 may also be termed a pedicle screwconstruct, pedicle screw coupling device, or the like.

The coupling construct 31 includes a head 34, a sleeve 36, a collar 38and a fixation element 40. The head 34 is configured, adapted and/oroperable for reception and retention onto the head 42 of the pediclescrew 32 and to be fixedly, but releasably, angularly oriented withrespect to a longitudinal axis of the pedicle screw 32 (e.g. the shank42 of the pedicle screw 32). The head 34 is further configured, adaptedand/or operable for releasable retention or holding of a spinal rod. Thecoupling construct 31 is received onto the pedicle screw head 44 and isreleasably fixable (positioned) relative thereto within a range ofangular orientations. In accordance with an aspect of the subjectinvention, the fixing, retaining or holding of the spinal rod to thecoupling device 31 does not fix the angular orientation of the couplingdevice 31 relative to the pedicle screw head 44. Rather, as explainedfurther below, the angular orientation of the head 34 and pedicle screw32 is releasably fixed independent of the releasable affixation of thespinal rod to the head 34. Thus, in one manner of implanting, theangular orientation of the head relative to the pedicle screw isselected and fixed while the spinal rod is received in the head but notfixed thereto. The spinal rod is then releasably affixed to the headafter the angular positioning of the head/pedicle screw.

The head 34 of the coupling construct 31 is characterized by a body 48having an axial bore 50 therethrough that defines a first end or opening51 and a second end or opening 52. The body 48 is generally cylindricalor tubular shaped with a slight narrowing on the middle outside of thebody 48. The bore 50 is sized such that at the first end 51, a pediclescrew shank and head may easily pass. The bore 50 is sized such that atthe second end 52 the pedicle screw shank may pass, but the pediclescrew head will not. A radially inward slope 68 is provided at thesecond end 52 for capturing the pedicle screw head but allow forrotational and angular movement of the head 34 on the pedicle screwhead. This allows the angular orientation of the head 34 to be changedrelative to the pedicle screw

A slot 58 is formed in the body 48 having an axis that is essentiallyperpendicular to the bore 50. The slot 58 extends through both sides ofthe body 48 to define a generally U-shaped channel therebetween and aseat or seating surface 60 on one side of the body 48 and a seat orseating surface 61 on another side of the body 48. The slot 58 is sizedto receive a spinal rod. The spinal rod is retained against the seats60, 61 when affixed to the head 34 as described herein. The bore 50 andslot 58 define first and second walls 52 and 54 that extend from the end52. The walls 52 and 54 are generally arcuate shaped and have a heightsufficient to extend over a spinal rod and receive the collar 38 and thefixation device 40.

The inside of each wall 52 and 54 includes a respective groove or slot64 and 66. Each slot 64, 66 extends or begins (provides an opening) atopposite (180°) sides of the respective wall 52, 54 and extends a radialdistance about the wall 52, 54. Preferably, the slots 64, 66 do notextend to the other side of the respective wall 52, 54. Each slot isadapted to receive a flange of the collar 38. In addition, the body 48includes first notch 65 on the inside periphery of the wall 54, and asecond notch 67 on the insider periphery of the wall 52. The notches 65,67 are sized and/or configured to receive a detent of the collar 38.These features allow the collar 38 to be received and rotated into asnap fit retained or locked position relative to the head 34.

The sleeve 36 or taper lock element of the coupling construct 31 isadapted, configured and/or operable to be received in the head 34 and tointeract with the pedicle screw head and collar 38 for providingfixation of an angular orientation or position of the head 34 (couplingconstruct 31) relative or with respect to the associated pedicle screw.The sleeve 36 is characterized by a body 70 having an axial bore 72therethrough that defines a first end or opening 73 and a second end oropening 74. The body 70 is generally cylindrical or tubular shaped. Aslot 80 is formed in the body 70 having an axis that is essentiallyperpendicular to the bore 72. The slot 80 extends through both sides ofthe body 70 to define a generally U-shaped channel therebetween and aseat or seating surface 81 on one side of the body 70 and a seat orseating surface 82 on another side of the body 70. The slot 80 is sizedto receive a spinal rod. The spinal rod is retained against the seats81, 82 when affixed to the coupling construct 31 as described herein.The bore 72 and slot 80 define first and second walls 76 and 78 thatextend from the end 74. The walls 76 and 78 are generally arcuate shapedand have a height sufficient to extend over a spinal rod and be abuttedby the collar 38 during angular position fixation of the couplingconstruct 31 to the pedicle screw.

Referring additionally to FIG. 2, a sectional view of the sleeve 36 isshown. The bore 72 is defined in the body 70 such that the inner sidewall 84 of the wall 76 is angled or tapered as is the inner side wall 86of the wall 78. The upper ends 77 and 79 of the end 73 (walls 76 and 78)are thus thicker than the ends 85 and 87 of the end 74 (walls 76 and78). Thus, when pressure is applied to the end 73, the end 74 will tendto spread or flare radially outward. As best seen in FIGS. 4 and 5,pressure and this process fixes or wedges the construct 31 relative tothe screw 32.

The collar 38 of the coupling construct 31 is adapted, configured and/oroperable to be releasably lockingly received in the head 34 and providea means or manner in which the angular position or orientation of thecoupling construct 31 relative to the pedicle screw on which it iscoupled. The collar 38 has a body 92 of a generally annular or ringshape. The body 92 defines a first or upper annular side or surface 93.The inner surface 94 of the annular body 92 is threaded to receive alike threaded component or element (e.g. the fixation element 40). Twocutouts or notches 96 and 97 are provided in surface 93 that are sizedto receive an insertion tool for rotating the collar 38 into positionrelative to the head 34.

For this purpose the body 92 includes two elongated flanges 100, 101disposed on the annular outer periphery of the body 92, preferablyopposite one another. The flanges 100, 101 are sized to be received inslots 64 and 66 of the head and are thus configured and/or sizedaccordingly. Moreover, two detents 98 and 99 are disposed on the upperrim of the surface 93. The detents 98, 99 are sized to be received inthe notches 65, 67 of the head when the collar 38 is rotatably receivedin the head 34.

Referring additionally to FIG. 3, the annular or ring shaped lower endor surface 102 of the body 92 is shown. The lower surface 102 contactsthe sleeve for compression against the pedicle screw head. The lowersurface 102 has a first detent structure 104 having a ramped portion 105and defining a stop surface 106, and a second detent structure 108having a ramped portion 109 and defining a stop surface 110. The detentstructures 104, 108 are positioned at an angle α with respect to acenterline, and adjacent a beginning of a flange 100, 101. Thus, thedetent structures 104, 108 line up with the rod slot 58 of the head 34but are rotated into pressure engagement with the upper surface 77, 79of the sleeve 36. This is best illustrated in FIGS. 4 and 5 which showcross sectional views of the coupling construct 31 on the pedicle screw32.

The fixation element 40 of the coupling construct 31 is adapted,configured and/or operable to releasably fix a spinal rod to thecoupling construct 31 and is received in the threaded opening 94 of thecollar 38. As such, the fixation element or set screw 40 has a generallyannular body 112 having external threads 116 on the outer annularperiphery thereof. Additionally, the body 112 includes a configured bore114 for receiving an insertion tool. Insertion of the fixation element40 into the collar 38 presses and fixes the spinal rod to the couplingconstruct 31 independent of the fixation of the orientation of thecoupling construct 31 relative to the pedicle screw 32. Again, this isbest illustrated in FIGS. 4 and 5.

Referring specifically to FIGS. 4 and 5, the manner in which thecoupling construct 31 is received on a pedicle screw head 44, receives aspinal rod 25 (shown in dashed line), and allows fixation of the angularorientation of the coupling construct 31 relative to the pedicle screw32 independent of the fixation of the spinal rod 25 to the couplingconstruct 31 is best seen. FIG. 4 shows that the collar body 92, wheninserted into the head 34, provides downward pressure on the upper ends77, 79 of the sleeve walls 76, 78. The downward pressure is transmittedto lower ends 85, 87 that spread slightly due to its taper to bindagainst the pedicle screw head 44. Of course, removal of the collar body92, relieves pressure on the pedicle screw head 44 to allow angularpositioning of the coupling construct 31 relative thereto. FIG. 5 showsthe receipt of the spinal rod 25 within the channels 58 and 80 of thehead 34 and the sleeve 36 respectively. The rod 25 rests upon the seats60, 61 of the head 34 and the seats 81, 82 of the sleeve 36. The seats60, 61, 81, 82 hold the rod 25 above the pedicle screw head 44. Thefixation elements 40 (e.g. set screw) is threadedly received in thethreaded bore of the collar body 92. The set screw 40 provides pressureagainst the rod 25 to fix the rod 25 relative to the coupling construct31 independent of the coupling head/pedicle screw fixation.

FIG. 6 shows an assembled coupling construct 31 retaining the spinal rod25 and illustrating the various angular positions or orientationspossible between the coupling construct 31 and the pedicle screw 32. Theorientation of the pedicle screw 32 is shown in various positionsrelative to the coupling construct 31 for ease of illustration. Thecoupling construct 31 is infinitely variable from 0° (i.e. a verticalaxis of the coupling construct 31 coaxial with a longitudinal axis ofthe screw 32 or shaft 42 thereof) up to about 90° (i.e. at an angle β ofabout 45°±2° from the vertically aligned screw shaft axis and thecoupling construct 31).

Referring now to FIGS. 7 and 8, there is depicted two views of anotherexemplary embodiment of a head or coupling member/element for a spinefixation coupling construct that is generally designated 120. The head120 is fabricated from a suitable surgical material such as a metal,metal alloy, polymer or the like as is the other heads and/or componentsof the present invention. The coupling member 120 is characterized by abody 122 that, in one side profile defines a snub toed boot or shoeshape. This, along with an enlarged pedicle screw head reception area orchannel 138 allows the construct to rotate approximately −10° (± a fewdegrees) to approximately 90° (± a few degrees) in one or more planes.

The body 122 has a central bore 124 defining a first end 126 and asecond end 128. The first end 126 receives a pedicle screw (shank endfirst) while the second end 128 allows the pedicle screw shank to extendtherethrough, but swivelbly retain or hold the pedicle screw head inlike manner to the head 34 of the pedicle screw construct 31. The bore124 defines a first wall 132 extending from a lower portion of the body122 and a second wall 134 extending from the lower portion of the body122. The walls 132 and 134 are arcuate and preferably, but notnecessarily, formed as portions of a circle. The respective outersurface of each wall 132, 134 includes respective threading 133, 135,while the respective inner surface of each wall 132, 134 includesrespective elongated, arcuate channels 129, 131. The walls 132, 134 areshaped to form a U-shaped channel 130 therethrough. The channel 130 issized to receive a spinal rod therein. Moreover, the channel 130 definesseats 136, 137 that support the spinal rod.

As best seen in FIG. 8, the pedicle screw head retention end 128 of thehead 120 includes a cutout portion or notch 138 that intersects with thebore 124 to create a slot, channel, groove or the like at the end 128.The configured channel 138 allows the shank of a pedicle screw to swivelthrough an angle γ defined as between a longitudinal axis of the bore124 and a perpendicular thereto. Thus, the head 120 is releasablypositionable on the pedicle screw head from 0° (wherein the bore 124 iscoaxial with the pedicle screw shaft, such as is depicted in FIG. 2) toapproximately 90° (wherein the pedicle screw shaft axis is perpendicularto the axis of the bore 124). Of course, the head 120 may rotate aboutthe pedicle screw head in an unrestricted manner (360°) regardless ofthe position of the pedicle screw shaft relative to the axis of the bore124. Particularly, the end 128 (including slot 138) allows the captureof the screw head such that the coupling member 120 may rotate 360°about the head of the bone screw. Particularly, the slot 138 allows thearticulation of the bone screw from an approximately a −10° (± a fewdegrees) position (where a longitudinal axis of the coupling member 120is coaxial with a longitudinal axis of the bone screw shaft), to a +90°(± a few degrees) position and to all continuous angles therebetween.

Referring to FIGS. 9 and 10 there is shown two perspective views of analternative embodiment of a coupling member or head generally designated140. The coupling head 140 retains the ability to allow movement betweenit and a bone screw in like manner as the coupling head 120 of FIGS. 7and 8. The coupling member 140, however, incorporates features notpresent in the coupling member 120 of FIGS. 7 and 8.

The coupling member 140 has a body 142 that is formed in a generallyblock rectangular shape, particularly with respect to a longitudinalaxis transverse to a bone screw attached thereto and in a 0°orientation. The body 142 may take on different forms consistent withthe principles of the subject invention. The body 142 defines anelongated channel 144 that is sized to receive a length of a spinalfixation rod. The rod channel 144 defines rod seats 153, 154. Moreover,the rod channel 144 is slightly enclosed by an arched portion 148 of thebody 142. The arched portion 148 axially extends over a bone screw bore146 in the body 142 and includes a cutout portion 149 to allow for theinsertion of a collar (see, e.g. FIG. 11) and/or a bone screw. At leastone, and shown here as two, set screw or rod fixation element bores 150and 152 are disposed in the arched portion 148. The side loads thespinal rod for releasable fixation of the spinal rod to the head 140.Each bore 150, 152 is threaded to receive a threaded set screw (see e.g.element 40 of FIG. 1) that releasably retains or affixes the fixationrod therein once the fixation rod is in a proper position. The archedportion 148 provides an angled or side mount (rather than from the top)for receipt of the spinal rod. The opening of head 140 is at anapproximately 45° offset.

The bottom 156 of the head 140 includes a slot 158 in communication withthe bore 146 and configured in like manner to the slot 138 of head 120.This allows the same freedom of movement for variable angularpositioning of the head 120 relative to a received pedicle screw. Theopening 158 is tapered to retain the rounded head of a bone screw and/orcollar from exiting from the coupling member 140.

Referring to FIG. 11, an exemplary embodiment of a collar, generallydesignated 160, that may, and preferably but not necessarily is,utilized with the coupling head 140. The collar 160 is characterized bya body 162 having a configured bore 168 along an axis of the cylindricalbody 162. A first concave surface 164 is provided at one end of the body162 and is shaped as a portion of a cylinder that has a longitudinalaxis that is transverse to the axis of the body 162 (and/or bore 168).The concave surface 164 defines first and second ends 172, 173.

A second concave surface 166 is provided at another end of the generallycylindrical or tubular body 162 opposite the first concave surface 164.The second concave surface 166 is likewise shaped as a portion of acylinder that has a longitudinal axis that is transverse to the axis ofthe body 162 (and/or bore 168). The concave surface 166 defines firstand second ends 174, 175. The first and second concave surfaces 164 and166, however, are disposed at essentially right angles to each otherwhile the ends 172, 173 and 174, 175 are opposite one another. The firstand second concave surfaces 164, 166 provide an hourglass configurationto the collar 160 is cross section. The first and second concavesurfaces 164, 166 respectively receive the head of a bone screw and afixation rod for applying a fixation pressure from the rod to the screw.

Referring to FIG. 12 there is depicted an exemplary embodiment of aspine fixation construct, utilizing a pedicle screw 32 and the couplinghead 140, holding a spinal rod 170. The pedicle screw 32 is positionedin a 0° position as one limit of its pivoting range and shown in dashedlines in a 90° position as the other limit of its pivoting range. Itshould be appreciated, however, that the coupling member 140 may bepositioned in the various manners as described for the construct of FIG.6. Not shown, are set screws that would be inserted into the set screwbores 150, 152 of the body 142 in order to fix the longitudinalpositioning of the spinal rod 170. Likewise, the collar 160 is notshown.

FIG. 13 depicts a side sectional view of the construct of FIG. 12,particularly taken along the axis of the pedicle screw shaft 42. Thespinal rod 170 rests against the surface 164 of the collar body 162while the pedicle screw head 44 is disposed adjacent the surface andcontacted by the sides thereof. Loading of the spinal rod 170 by setscrews (not shown) through the set screw bores 150, 152 results inpressure upon the collar 166 which forces against the pedicle screw head44 thereby fixing its position relative to the coupling head 142. Thus,the depiction of FIG. 13 illustrates the cooperation and/or interactionof the rod 170, the collar 160 and the head 44 of the screw 32. Itshould be appreciated that the various components are not necessarilysized accordingly. As connecting rod 170 is urged downwardly into thesocket of the collar body 162 by set screws (not shown) extendingthrough the set screw bores 150, 152, the socket collar body pressesagainst the head 44 of the screw 32. This creates a friction fit to lockthe orientation of the coupling head 140 relative to the rod 170 and thescrew 32.

Referring now to FIGS. 14-18, there is depicted various views of anotherpedicle screw construct 190 having a coupling construct 191 and apedicle screw 32. FIG. 14 provides an exploded view of the pedicle screwconstruct 190 having a coupling construct 191 in exploded view forattachment onto the pedicle screw 32. The coupling construct 191includes a head 192, a sleeve 194 that is received in the head 192, arod retention element 196 that is received by the head 192, and a setscrew or fixation element 198 that is also received by the head 192.

The head 192 of the coupling construct 191 is characterized by a body200 having a shape that melds at least some of the features of thevarious coupling heads of the present invention. Particularly, the body200 has a bore 202 for reception of the pedicle screw 32 therethroughand extension of only the shaft 42 thereof through the configured end204 of the body 200, the head 44 of the screw 32 being rotationallycaptured, retained or held by the configured end 204. The configuredend, as best seen in FIGS. 16 and 17, is shaped or channeled in likemanner to the channels 138 and 158 of the coupling heads 120 and 140. Assuch the head 192 provides the same rotation and swiveling range ofmotion as the heads 120 and 140. The body 200 further defines a spinerod channel 206 for reception of a spinal rod. Rod seats 207, 208provide support for the rod against the head 192. The body also has atilted or angled, generally annular top portion 212 having a threadedbore 214. The top portion 212 is angled to provide an angled inlet for aspinal rod into the rod channel 206. As best seen in FIG. 15, the topportion 212 creates a rod reception inlet that is angled ( ) relative toa 0° position. This provides angled loading against the rod by the rodretention element 198, whose nose 236 as seen in FIG. 15, cups aroundand retains a spinal rod.

The sleeve 194 of the coupling construct 191 has a generally cup-shapedbody 224 with a saddle-shaped cavity 222 that defines a front side 224and a rear side 223 having a shaped that mimics the front 210 of thebody 200 of the head 192. As best seen in FIG. 17, the body 220 providesa seat for a spinal rod and a fixation element for the pedicle screwhead 44. Thus, as a spine rod is loaded as described below, the sleeve194 is loaded against the pedicle screw head 44 to fix the position ofthe construct 191 relative to the pedicle screw 32.

The rod retention element 196 of the coupling construct 191 ischaracterized by a body 230 having a generally flat top surface having ahole 232 therein. The body 230 also defines an arcuate portion 234 and aconfigured nose or protrusion 236. The nose 236 cradles the spinal rodwhen assembled.

The set screw or fixation element 198 of the coupling construct 191 ischaracterized by a generally annular or disk shaped body 240 havingthreading 242 on the external annular periphery of the body 240. Thethreading is sized to thread with the threaded bore 214 of the topportion 212 of the head 214 and thus to be inserted therein. Thefixation element 198 further includes a configured socket 244 on a topsurface thereof for driving the fixation element 198, and a boss 246 ona lower surface thereof. The boss 246 is sized to register with the bore232 of the rod retention device 196 when assembled (see e.g. FIG. 17).

FIG. 19 depicts the coupling construct 191 on the pedicle screwconstituting the pedicle screw construct 190 having received a spinalrod 250. The coupling construct 191 is shown before fixation of thespinal rod to the coupling head 200 and before fixation of theorientation of the coupling head 200 relative to the screw head 44. FIG.20 depicts the fixation of the spinal rod to the coupling head 200 andthe fixation of the coupling head orientation relative to the screw head44. The set screw 198 has been received in the bore of the top portion212 such that the rod retention element has loaded or moved intopressure engagement with the rod 250. The nose 236 can be seen providingconfigured retention of the rod 250. It should be appreciated that whilethe screw is shown in a 0° position, not withstanding rotation of thehead 200 relative to the screw, the screw may be positioned from 0° toapproximately 90°.

Referring now to FIG. 21, there is depicted another embodiment of acoupling head generally designated 260. The coupling head 260 is similarto the coupling head 192 of the coupling construct 191, but ratherprovides a side or 90° entry into a rod channel 274. Particularly, thecoupling head 260 is characterized by a body 262 having a generallytubular shape having a central bore 264 that extends from a configuredend 278 (configured for 90°+screw angulation) to end 272. The bore 264is threaded at end 272 to receive a set screw (e.g. set screw 198). Anelongated neck 262 terminates in a rounded top portion 270. The topportion 270 is perpendicular to the bore 264 to provide side entry(approximately 90°) for the spinal rod relative to the axis of the bore(0°).

FIGS. 22 and 23 depict the coupling head 260 as a coupling construct andpedicle screw construct releasably fixedly holding or retaining a spinalrod 280. In addition to the set screw 288 having a configured drivingsocket 290, the coupling construct includes a collar 282 that fits overthe pedicle screw head 44 and provides a seat for the rod 280. Thecollar 282 cradles the rod 280 to maintain the rod 280 in place. The setscrew 288 provides pressure against the rod 280 which provides pressureagainst the collar 282 which provides pressure against the head 44 toreleasably fix the rod 280 to the head 262 and the head 262 to the screw32. Moreover, the configured opening 278 of the head 262 is sized toallow an approximately 180° range of motion of the head relative to thescrew/screw shaft as represented for ease of understanding by the changein positions of the screw (90° on either side of the 0° position) asindicated by the angle θ in FIG. 23. The coupling head also rotatesabout the head 44.

It should be appreciated that the figures showing the pedicle screw invarious orientations or positions illustrates the various orientations(or limits of a continuous range of orientations or positions) thecoupling head or construct may assume in accordance with the presentprinciples, since the pedicle screw will be fixed in orientation whenimplanted into a vertebra. As such, the coupling head or constructmoves, pivots or folds with respect to the screw and/or screw shaft(axis). It can thus be understood that the coupling head/coupling headconstruct pivots or folds downwardly with respect to the pedicle screwshaft/axis. When implanted, the pedicle screw axis may be deemed avertical, and therefore the head/construct preferably, but notnecessarily, moves from a vertical (0°) or near vertical (−5°) positionto a horizontal (45°) or near horizontal (±5°) position. It should alsobe appreciated that the elongated channel, slot or end of the couplinghead/coupling head construct is preferably, but not necessarily,oriented substantially perpendicular to the longitudinal axis of aretained spinal rod. Thus the arc of movement of the coupling head orconstruct is along an arc that is perpendicular to the longitudinal axisof the spinal rod. In FIG. 23, for example, that range or arc ofmovement is given by θ.

The present invention provides advantages over the teachings of theprior art with respect to pedicle screw construct technology. Theprinciples accompanying the present invention allows the present pediclescrew construct to be used with greater accuracy. This may ultimatelyincrease the efficacy of an established procedure. The present pediclescrew constructs and/or coupling constructs used along with a bonescrew, may utilize various types of spinal rods such as straight orpre-curved rods may be used. The rod may be bent or curved in one ormore locations.

The subject constructs provide several key attributes not present in theprior art and not necessarily discussed above. The subject pedicle screwconstruct has the ability to reduce stack height by approximately 50%over prior pedicle screw constructs. Stack height is the overall totalheight of the installed construct. Such reduction in stack heightreduces tissue distraction, reduces discomfort, and provides a reductionon construct loading that may lead to premature failure.

The subject pedicle screw construct also has the ability to fold(articulate) from a raised position of approximately −10° (±10°) toapproximately 90°±10°. The pedicle screw construct is operative,configured and/or adapted to releasably lock into any articulation anglefrom the −10° (±10°) to approximately 90°±10° position. In one form, thesubject pedicle screw construct also provides 360° rotation of thecoupling member with respect to the bone screw thereof. The bonescrew/coupling member also provides at least one other plane of relativemotion.

The present coupling constructs, such as the coupling construct of FIGS.15-23 allows the body or head thereof to be positioned relative to animplanted pedicle screw (and therefore the body or coupling constructrelative to the pedicle screw) to receive a spinal rod in a top loadingposition while the body is at least in and/or within a −5° arc relativeto a perpendicular of the pedicle screw (shaft). This allows the head torotate about the pedicle screw in a folded state to at least and/orwithin a 45° arc relative to the pedicle screw.

During implantation, the head is angled straight up and down relative tothe U-channel, the head is then angled parallel (through and to the atleast 45° arc) to the horizon (at least perpendicular to the pediclescrew shaft) to receive the set screw. Thereafter, the head is foldedover to where the back surface can be horizontal to the horizon in aneffort to lock up the system. The system, however, can be locked in anyarcuate and rotational orientation therebetween.

Use of the subject pedicle screw construct alleviates the need to usemultiple systems to produce the same surgical outcome. The subjectpedicle screw construct provides the surgeon with greater flexibilityduring the surgical procedure to adjust pathological anatomy. Forexample, current systems only allow several degrees of movement from thecenter to midline area. The subject pedicle screw construct allows thesurgeon to place the bone screws thereof and then adjust the positioningof the coupling member (stabilization link) intra-operatively withoutremoving the pedicle screws from the pedicle. The net effect is a moreforgiving system.

The subject pedicle screw construct also provides the surgeon with theability to adjust the system without disassembly. Particularly,adjustment of a connecting rod or of stack height can be accomplishedwithout disassembling the pedicle construct and/or removing a pediclescrew thereof. Current “tulip” designed pedicle screw constructs requirethat during each adjustment the surgeon fully assembly the system. Ifseveral adjustments are necessary, the potential to strip out thethreads within the tulip are high. If this happens, the entire pediclescrew would need to be removed, in which case the integrity of the wholeconstruct is eroded. This is not the case with the subject pedicle screwconstruct.

The subject pedicle screw construct is intended for use with the spine.Particularly, the subject pedicle screw construct is intended(non-exclusively) for patients with the following indications:

When used as a pedicle screw system in skeletally mature patients;

-   -   a. Severe (Grade 3 and 4) Spondylolisthesis at the L5-S1 joint;    -   b. Patients receiving fusion using autogenous bone graft only;    -   c. Patients who are having the device fixed or attached to the        lumbar and sacral spine (L3 and below); and    -   d. Patients who are having the device removed after the        development of a solid fusion mass.

When used as a pedicle screw system in skeletally mature patients, it isintended to provide immobilization and stabilization of spinal segments,as an adjunct to fusion, in the (non-exclusive) treatment of thefollowing acute and chronic instabilities or deformities of thecervical, thoracic, lumbar and sacral spine:

-   -   a. Degenerative spondylolisthesis with object evidence of        neurological impairment;    -   b. Fracture;    -   c. Dislocation;    -   d. Scoliosis;    -   e. Kyphosis;    -   f. Spinal tumor; and    -   g. Previously failed fusion (pseudoarthrosis).

Moreover, the subject spine fixation system, when used for anterolateralnon-pedicle screw fixation to the spine, is (non-exclusively) intendedfor the following indications:

-   -   a Degenerative disc disease (as defined as back pain of        discogenic origin with degenerative disc confirmed by history        and radiographic studies);    -   b. Spinal stenosis;    -   c. Spondylolisthesis;    -   d. Spinal deformities (e.g. scoliosis, kyphosis and/or        lordosis);    -   e. Pseudoarthrosis;    -   f. Tumor;    -   g. Trauma (e.g. fracture or dislocation); and    -   h. Previous failed fusion.

Still further, the subject spine fixation system/pedicle screwconstruct, when used for posterior non-pedicle screw fixation to thespine, is intended for the following indications:

-   -   a. Degenerative disc disease (as defined as back pain of        discogenic origin with degenerative disc confirmed by history        and radiographic studies);    -   b. Spinal stenosis;    -   c. Spondylolisthesis;    -   d. Spinal deformities (e.g. scoliosis, kyphosis and/or        lordosis);    -   e. Pseudoarthrosis;    -   f. Tumor;    -   g. Trauma (e.g. fracture or dislocation); and    -   h. Previous failed fusion.

The subject spine fixation system or pedicle screw construct differsfrom the prior art in the following ways. Particularly, there issubstantially greater surgeon flexibility when placing the bone screws.Due to the wider range of motion offered by the head or coupling member,the pedicle screws can be inserted and placed in the most favorableanatomical position. This can be done because the system is notconstrained by the connecting rods or the range of motion offered by theheads.

The subject system, in one form, is locked into place using a taper lockmechanism which reduces the stress applied to the locking screwmechanism thereof. This is a critical advantage as competing devices arelocked into place by utilizing a locking collar, rod and head interface.The present spine fixation system utilizes mechanical advantages ofusing dual tapered interfaces to apply virtually infinite locking forcewhile minimizing thread shear stresses.

The subject system allows for intra-operative adjustment of the systemwithout having to apply the locking mechanism or set screw. Due to theunique design of the head, a connecting rod can be inserted and retainedwithout installing the locking mechanism. This saves time, allows forgreater variability with placement and potentially will reduce the needto remove the screw and head due to stripped locking mechanism threads.

Range of motion of the subject invention is greater that the prior art.The present spine fixation system/pedicle screw construct articulatefrom center to midline −10°+95°. The range of motion cephalad and caudal(superior/inferior) is approximately ±45°. These ranges of motionsurpass all currently available spine fixation systems by at least 10°.

Reduction of stack height to reduce the stress, distraction and traumaon surrounding tissues. Also, reduced stack heights make the deviceinherently stronger, due to the reduced inertial moments placed on thedevice.

It should be appreciated that the above description is only exemplary ofthe principles of the subject invention. Therefore, other embodimentsare contemplated and within the present scope.

The screw is loaded into the various connecting components from the top(i.e. top loading). However, while not shown, it is contemplated thatthe coupling or connection of the screw to the connecting component maybe accomplished from the bottom (i.e. bottom loading). A bottom loadingconnecting component may allow for greater folding and/or flexibility ofthe connecting component relative to the screw.

While this invention has been described as having a preferred design,the present invention can be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, of adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains and that fallwithin the limits of the appended claims.

1. A pedicle screw coupling device for holding a spinal rod relative toa pedicle screw, the pedicle screw coupling device comprising: acoupling head having a bore therethrough and defining a first end sizedto receive a pedicle screw shaft and a pedicle screw head of the pediclescrew and a second end sized to allow the pedicle screw shaft to passthrough but rotatably retain the pedicle screw head, the coupling headfurther including a channel configured to receive the spinal rod; acollar releasably rotatably coupled directly to the coupling head; asleeve received in the coupling head bore between the pedicle screw headand the collar, the sleeve having a first end abutting the pedicle screwhead and a second end abutting the collar; a spinal rod retentionelement configured to be received through the collar and to fix thespinal rod received in the channel of the coupling head relative to thecoupling head; wherein the collar applies pressure to the pedicle screwhead through the sleeve to fix an orientation of the coupling headrelative to the pedicle screw head responsive to the collar beingrotatably coupled directly to the coupling head; wherein the fixation ofthe spinal rod relative to the coupling head is separate and independentof the fixation of the coupling head relative to the pedicle screw head.2. The pedicle screw coupling device of claim 1 wherein the sleeveincludes a sidewall having a taper extending from the second end to thefirst end.
 3. The pedicle screw coupling device of claim 1 wherein thecoupling head has undercut channels that mateably receive the collar ina snap fit fashion during fixation.
 4. The pedicle screw coupling deviceof claim 1 wherein the coupling head has threads that mateably receivethe collar during fixation.
 5. The pedicle screw coupling device ofclaim 1 wherein the spinal rod channel of the coupling head maintainsthe spinal rod axially above the pedicle screw head.
 6. The pediclescrew coupling device of claim 5 wherein the spinal rod is maintainedspaced apart from the pedicle screw head.
 7. The pedicle screw couplingdevice of claim 1 wherein the coupling head has a pair of grooves thatmateably receive a pair of flanges on the collar during fixation.
 8. Thepedicle screw coupling device of claim 7 wherein the collar comprises afirst detent that engages the sleeve when rotated.
 9. The pedicle screwcoupling device of claim 8 wherein the first detent is located on abottom surface of the collar adjacent one of the pair of flanges, andwherein the collar comprises a second detent located on the bottomsurface adjacent the other of the pair of flanges.
 10. The pedicle screwcoupling device of claim 9 wherein each of the detents comprises aramped portion and a stop surface that are rotated into pressureengagement with an upper surface of the sleeve.
 11. The pedicle screwcoupling device of claim 9 wherein the spinal rod is received in theslot and retained against the first seating surface and the secondseating surface.
 12. The pedicle screw coupling device of claim 1wherein the collar comprises a pair of notches sized to receive a toolfor rotating the collar relative to coupling head.
 13. The pedicle screwcoupling device of claim 1 wherein the sleeve comprises a slot thatdefines a first seating surface and a second seating surface.
 14. Acoupling device for holding a spinal rod relative to a pedicle screwhaving a pedicle screw shaft and a pedicle screw head, the couplingdevice comprising: a coupling head having a bore and a channel, the borehaving a first end sized to allow the pedicle screw shaft and thepedicle screw head to pass through and a second end sized to allow thepedicle screw shaft to pass through but rotatably retain the pediclescrew head, the channel configured to receive the spinal rod; a sleevereceived in the bore of the coupling head and having a first end and asecond end, the first end configured to abut the pedicle screw head; acollar releasably rotatably coupled directly to the coupling head andabutting the second end of the sleeve, wherein an angular orientation ofthe coupling head is fixed relative to the pedicle screw by pressureapplied by the collar to the pedicle screw head through the sleeveresponsive to the collar being rotatably coupled directly to thecoupling head; a spinal rod retention element received through thecollar to fix the spinal rod relative to the coupling head; wherein theangular orientation of the coupling head relative to the pedicle screwhead is separately and releasably fixed independent of the releasablefixation of the spinal rod to the coupling head.
 15. The coupling deviceof claim 14 wherein an exterior feature of the collar is coupled to aninterior feature of the coupling head by a rotating movement of thecollar relative to the coupling head.
 16. The coupling device of claim15 wherein the exterior feature of the collar comprises a flange and theinterior feature of the coupling head comprises a groove.
 17. Thecoupling device of claim 16 wherein the collar comprises a first detentthat engages the sleeve when rotated.
 18. The coupling device of claim16 wherein the collar comprises a second detent, the first detent islocated on a bottom surface of the collar adjacent one of the pair offlanges, and the second detent is located on the bottom surface adjacentthe other of the pair of flanges.
 19. The coupling device of claim 16wherein each of the detents comprises a ramped portion and a stopsurface that are rotated into pressure engagement with an upper surfaceof the sleeve.